package experiment09;

public class experiment09 {
    public static void main(String[] args) {

        double s=1;
        int i=2;

        while (i<100){
            if(i%2==0) s=s-1/(double)i;
            else s=s+1/(double)i;
            i++;
        }
        System.out.println(s);
    }
}
